Retardation device for the recovery of projectile components



Aug. 25, 1959 M. l.. KEMPTON Erm. 2,900,907

RETARDATION DEVICE FOR THE RECOVERY OF PROJECTILE COMPONENTS Filed May 7, 1952 N N .m n* M .M m m vm um 9o m M O mL J. wm h H A l mwg c Y B l vla. llllnlllll 3 Sheets-Sheet 2 INVENTORS MARVIN L. KEMP TON BYEVERLYJ. WOR/(MAN M. L. KEMPTON ETAL RETARDATION DEVICE FOR THE RECOVERY OF PROJECTILE COMPONENTS Aug. 25, 1959 Filed May '7, 1952 M. L. KEMPTON ETAL 2,900,907

Aug. 25, 1959 RETARDATION DEVICE FOR THE RECOVERY OF PROJECTILE COMPONENTS 3 Sheets-Sheet 3 Filed May 7, 1952 I N VEN T RS MARv/N 1. KEMPro/v BY EVER/.Y J. woR/rMA/v @QM @7 /3 zzffw United rates @arent free RETARDATION DEVICE FOR THE RECOVERY GF PRUJEC'HLE CGMPONENTS Marvin L. Kempton and Everly J. Workman, Socorro, N. Mex., assgnors to the United States of America as represented by the Secretary of the Navy Application May 7, 1952, Serial No. 286,506

2 Claims. (Cl. 102-63) This invention relates generally 4to projectile recovery devices, and more particularly to retardation devices for the recovery of projectile components.

The techniques employed in modern warfare require the testing for ruggedness of relatively sensitive electrical and mechanical devices in projectiles in ight, such as proximity fuzes and the like. The development and production of these devices for modern and future guns are facilitated greatly by the possibility of recovering projectile components after flight without these components having been subjected to signicant forces and shocks beyond those caused by the gun, and by normal flight conditions.

011e conventional way to recover projectile components, such as fuzes, is by a technique known as vertical recovery. This technique applies readily to guns which can be fired vertically, and which have relatively stable projectiles. The procedure is to tire the projectile at some small departure or angle from the vertical (5 to 20 mils), and collect it in an impact area at some small and reasonably safe distance from the gun (500 to 1,000 yards). A well-stabilized projectile will, under these conditions, return to the ground base iirst with a large amount of residual spin. If the surface of the ground is reasonably soft, the impact accelerating force may be considerably less than experienced in the gun.

This procedure or technique has been used successfully on guns, such as the 57 mm, 90 mm, 5"/38, 5/54, 3"/70 and the 120 mm.

Acceleration gages installed in such projectiles over a period of time have indicated, however, that frequently these impact acceleration values may be sufiiciently large to invalidate the testing technique. This happens, for example, when the surface of the ground is relatively hard, when the projectiles strike rocks or other hard objects, and/or when a large yaw angle exists at the time of impact.

In all of the guns mentioned above, it has been necessary to mount the gun on an incline in order to provide elevation angles of 90 or more, Although stable Hight conditions on the base-first, downward trajectory of the projectiles exist for the above guns under still air conditions, high winds aloft and sheer wind situations may cause tumbling. lt is to be remembered, of course, that the stability may be quite dilierent in this reverse direction of travel due to shifting of center of pressure and other aerodynamic effects.

When larger caliber, and possibly higher velocity guns are developed, it may be possible that tumbling may result in the lower atmosphere due to high velocity of fall acquire in rare air aloft, as well as from other shape factors.

'llhe depth of penetration of the projectile depends upon a great number of factors, such as impact velocity, mass of projectile, ratio of mass to length, amount of boattailing, and hardness of the ground. It has been found at some proving grounds, for example, that the depth of penetration has ranged from one (1) to twelve 12) feet for all projectiles.

This method or procedure as set forth above has been very effective as a proof device, and, in fact, has been of tremendous aid in the development of radio proximity fuzes of various types. However, it is cumbersome, laborious, and in many cases misleading.

lt is one of tlhe objects of this invention, therefore, to provide a retardation device for the recovery of projectile components which is simple and reliable in operation.

To provide a device for the recovery of projectile components that is inexpensive and capable of being manufactored by reasonably standard prccesses,.and which can be reused, are also other objects of this invention.

And another object of this invention is to provide a retardation device for projectile component recovery that can be installed in standard, or slightly medied standard projectiles.

To provide a projectile component recovery device which will allow for the operation of thel components being tested in the gun and in flight without introducing new causes of failure which might result from such effects as setback, side slap in the gun, vibrations during Hight, and in the case of proximity fuzes, changes in the loading of the oscillator, are also other objects of this invention.

While certain features and objects of the invention are generalized above, other objects and many of the attendant advantages will be appreciated and understood most readily from a disclosure of a specific embodiment thereof, as illustrated in the accompanying drawings and described herein, and in which:

Fig. 1 is a .longitudinal section, partly in elevation, of a projectile embodying one embodiment of the invention;

Fig. 2 is an exploded view of the projectile shown in Fig. l;

Fig. 3 is a cross-section on line 3 3 of Fig. 1;

Fig. 4 is an enlargement of the delay mechanism of Fig. l;

Fig. 5 is a perspective view of a projectile component, showing the retardation elements in extended condition;

Fig. 6 is a longitudinal section, partly in elevation, of a projectile embodying a second embodiment of the invention; and

Fig. 7 is a diagrammatic representation of a projectile component recovery range, with projectiles made in accordance with invention being recovered.

In accordance with the present invention, a projectile, such as a 3/50 rotating projectile, is modified by cutting oil two rings from the front end of the projectile, a cavity is bored in the projectile to form a cylindrical wall, and then the base of the projectile is drilled. A plurality of rods made from 1/s-inch diameter steel, each 6%-inches long after forming, are bent and weldedinto the two rings cut from the 3/50 projectile. This cylindrical array of rods is assembled into a projectile cavity ahead of a flange on a Duralumin (hereinafter to be referred to as dural) ejecting cup.

A dural bushing is screwed into the space normally occupied by the auxiliary detonator of a proximity fuze. This bushing includes part of a time delay mechanism having a ring pin. The time delay mechanism is in communication with a slow burning explosive train and slow burning ejecting powders.

Upon operation of the proximity fuze when the projectile is in substantially horizontal flight, such as by a target or by pulsing, the squib contained therein is detonated and it, in turn, sets off the explosive train and the ejecting charge. The explosive gases from the charge push the fuze and the cylinder of rods as a unit out of and ahead of the projectile. Under the influence of centrifugal force created by projectile spin, the rods are bent outwardly and substantially transversely to the longitudi` nal axis of the fuze so that upon fall thereof, the rods serve as a retardation or braking arrangement which allows the fuze to be recovered intact from a projectile component recovery range.

Referring now to the drawings, there is shown in Fig. l a 3"/50 anti-aircraft projectile 10 comprisinga body 12 with a fuze 14, such as a radio-proximity fuze, or time fuze, mounted in its forward .nose portion 16, a retardation device 18, a time delay mechanism 20, and an ejecting charge 22 located in a chamber in projectile 10` near its base24. It is to be emphasized that the invention to be described now is not limited in application to 3/50 anti-aircraft projectiles, but can be used with other types of anti-aircraft and field artillery projectiles to recover projectile components, such as fuzes and the like.

The standard projectile 10, as shown in Fig. 1, is modified by cutting two rings 26 and 28 from the forward end 16 thereof, boring a cavity 30 to form a cylindrical wall 32, and then drilling a bore 34 in the base 24.

' Forty-eight (48) rods 36 made from 1s-inch diameter steel, each 63/a-inches long after forming, are bent as indicated by 38, and are then welded, as indicated by welds 40, into the two rings 26 and 28 cut from projectile 10, as shown in Figs. 1 and 2. This cylindrical array of rods comprises the retardation device 18, Which is assembled into the projectile cavity 38 ahead of the flange 41 on the dural ejecting tube 42.`

A dural bushing 44 is secured, by screws 46, into the recessesnormally occupied by the auxiliary detonator of the' fuze 14.

Fuze 14 or other components, together with retardation device 18 can be ejected in several diferent ways, such as premature action of the fuze 14, action of the fuze 14 'on a target, pulsing of the fuze 14, or by means of the auxiliary time-delay mechanism 20 without fuze action.' The structural arrangement for accomplishing time-delay operation will now be described.

This 'auxiliary time-delay mechanism 20 is placed inside of a dural lead-in tube 48 in such a manner that it is firmly held on the axis of rotation of projectile 10. This is accomplished by placing one end 49 of tube 48 in a bore 50 of bushing 44, and the other end 52 in the bore 34 located thebase 24 of projectile 10.

`This delay mechanism 20 comprises a brass striking hammer 54 which is` located in a bore 56 thereof and which is placed forward of the delay rnechanisms strikingnpin mechanismv58 located in bores 60 and 61 of tube 48'adjacent'to bore 56. Striking hammer 54k is held in place 'by` a l/e-inch diameter solid solder 'shear pin 62, which extends through the walls of tube 48 and through the jbrasshamm'er 54;, Brass hammer 54 weighs 0.0005 pound 'andywheu' actuated,v strikes the firing pin mecha'nisrnSS with* approximately four (4) to iive (5) inch-V pounds of kinetic energy. Y

`A steel cup 64,holding an igniting powder charge 66 is placed in end 52 of the tube 48. This cup is separated from'bore 61 by means of a disk 68 which has a bore 70 therein through which the firing or striking pin 71 of mechanism 58 passes. Steel cup V64 thus supports the delay mechanism 20 during setback in the gun.

The opposite end 49 of the tube I48 has a cylindrical bore 72 thereinv for receiving' a quantity of rifle powder 74 or the like. shown) of the fuze 14, firing through a bore 76 located in the forward end 78 of bushing 44. It is to be noted that bore 72 is spaced from bore 56 by a wall 79.

As previously pointed out, a Vmain ejecting charge 22 surrounds the dural lead-in tube 48 containing the delay mechanism.V Slow burning lpowders are generally used as the'e'jecting charge 22 in order to give sustained ejecting force for a longer period lwithout exerting excessive pressures.l By thisl arrangement, maximum acceleration force during ejection can be held to a fractionV of ,they

initial lsetbacl'cforces in the'gun.

'Fig'. 6,t there# illustrated ,a projectile ,v10 embodying Powder 74 is set off by the squib (notY the retardation device 18, but one in which no fuze action is possible since the cylindrical bore 72 in tube 48 containing the powder 74, as showin in Figs. 1 and 4, has been eliminated, and the brass hammer 54 is no longer in open communication with the blast effects from a squib` contained in the fuze 14. In this case, ejection of the projectile components are initiated by the time delay mechanism 20, previously described but which will be reviewed briey.

This time delay unit is located in a cylindrical dural tube 82 which has relativelythick walls. Tube 82 has transverse bores 84 which areV in communication with the main ejecting charge 22. The upper end 86 of tube 82 is closed, and'it abuts a solid cylindrical member or plug 88. MemberL 88 occupies the position normally occupied by the auxiliary -detonator of a fuze. This member 88 is maintained in position by a set-screw 90 located in the wall 9.2 ofthe fuze.`

In the embodiment shown in Figs.V 1, 2, 3, 4 and 5, ejection of the fuze 14, together with the Vretardationrdevice 18, as previously pointed out, can be accomplished either by premature action, action of a proximity fuze on a target, action of a fuze from a pulser, or by means of the auxiliary time-delay action.

The operation of the. invention will now be described. A projectile 10 having aproxrni'ty fuze 14 and embodying the structure shown in Fig. 1 is red from a gun 9i), as shown in Fig. 7. Gun 90 is elevated to an angle. so that projectile 10 will have substantially a horizontal trajectory, as indicated by 92.

If projectile 10 passes within the proper distance of a target, such as 94, proximity fuze 14 will function to set oifrasquib contained therein. Thepblast from the squib will pass through boreV or entrance '76. and will ignite the powder 74contained in chamber 72` o f tube 48. Upon explosion of this powder, the dural tubeV 48 isfractured and ejecting charge 22is ignited. The gases generated4 upon thevbuming of the ejecting charge 22 drivethe dural cup 42 forward, pushing out the fuze 14 and the cylinder of rods 36 of device 18 as a unit ahead of projectile 10i. Centrifugal force bends the rods 36 outwardlysomething like that shown in Fig. 5. The conservation of .angular momentum of fuze 14 imposes a rapid decrease in the rotational speed thereof as the retarding rods areV bent outward. Fuze 14, together with retardation device 18, falls to a recovery range 96 along trajectory 97 and can be recovered intact.` Projectile 10 continues alongV its normal trajectory 92.

Whenfit is desired to pulse the fuze14after aprescribed period of flight by the projectile talong Vits trajectory, a radio signal is sent to the fuze by means of. pulsing equipment 98 located near the recovery range 96. This signal -is used to operate the fuze 14. The fuze 14, and retardation device 18 are ejected together as a unitV as described previously. They fall` to therecovery range along trajectory 99.

`When it is desired to eject a projectile component or components without fuze action,.the auxiliary time-delay. mechanism 28 illustrated in Figs. 1 or 6 is used. UponV ring of theY projectile 10 from gun 90setback or inertia forces causethe brass hammer 54 -toshear the shear pin 62'and strikethe firing pin 71.of mechanism 58. This firingpin 71 passes through bore 70, and sets of the powder 66 contained therein. Upon ignition of powder 66, the gases generated .therefrom vcause duralV tube 48 to fracture and set off-thek main ejecting charge 22.v This charge, upon burning, ejects the retardation device 18V with ,the projectile components, andthesemembers fall` to the recovery range 96 along trajectory 102.

Obviously many modicationsand variations of the present invention are -possible in the light of the above teachings.. It is therefore to be understood that within thescopeof the appended claims the inventionmay beA practiced otherwise than .asv specifically described.`

What is claimed is:

1. The combination with a rotating projectile having a body and a fuze, said body having a cavity formed with a cylindrical inner wall and said fuze having an ejeeting tube in the cavity spaced from said cylindrical Wallg'of a retardation device including a pair of rings between the body and the fuze, an annularly arranged series of rods initially lying within the projectile and extending between the cylindrical wall and the ejecting tube, said rods being disposed in parallel, interengaging relation thereby to form a cylinder and having corresponding outer ends bent to extend between the rings for securement thereby, an ejecting charge in the projectile, and detonating means for the charge, said charge, upon detonation by said means and subsequent to discharge of the projectile from a gun, projecting the fuze and retardation device ahead of said projectile for exposing the rods, said rods being bent radially by centrifugal force for retarding the descent of the fuze.

2. The combination recited in claim 1, including a delayed action mechanism for the detonating means.

References Cited in the tile of this patent UNITED STATES PATENTS 

